The objective of this research is to develop a non-invasive test strip for the prediction of a women's fertility window. This test will be based on the semi-quantitative colorimetric determination of salivary divalent cations. The test will be simple-to-use, inexpensive, provide the accuracy of costly instruments and can be used in the in the clinic or home setting. PortaScience has investigated changes in concentrations of salivary electrolytes during a female's fertile period and determined that there is a translocation of divalent cations (specifically Mg++ and Ca++) away from the salivary glands. This translocation of cations occurs during a female's fertile period, three to four days prior to ovulation. This drop in concentration of cations can be used as an effective biomarker to predict a women's fertility period. The specific aims of this investigation are: Aim 1: Select a dye substrate that provides the sensitivity to detect 250 uM Mg++/Ca++; Aim 2: Identify stabilizers and membrane material for protecting the dye substrates; and Aim 3: Build and evaluate the performance of test strips and define specifications for performance. The potential US market for fertility monitoring is 500 million dollars. [unreadable] [unreadable] [unreadable]